This paper highlights the top quartile performance well delivery of Yetagun In-fill Phase 6 drilling campaign in Yetagun gas field, offshore Myanmar. Drag, Torque, Hook load and Stand Pipe Pressure that occur in an ERD well is typically higher than conventional well due to long horizontal displacement and high lateral inclination angle. Hence, the importance of planning process, execution, drilling practices and lesson learnt which essentially resulting in a successful drilling operation were discussed in the paper. PETRONAS Carigali Myanmar Limited (PCML) successfully drilled three in-fill wells: YA-01, YA-05, and YA-12ST1 which were classified as ERD based on extended reach industry experience plot with the objective to maintain the gas production rate. Excellent planning process and good teamwork among the project team members were required to tackle all the technical issues as well the environmental and logistical challenges. The unique and challenging design for YA-05 as compared to others where it has the longest tangent length which fall within 70-80° sail angle. YA-01 and YA-12ST1 were classified as ERD medium reach class design, thus require specific ERD drilling, hole cleaning, ECD monitoring, tripping and backreaming practices to ensure success of the well. The challenges in designing ERD wells were multiple such as high torque and drag, loss circulation, well collision, differential sticking, borehole instability, hole cleaning, longer open hole interval, high stand pipe pressure and high temperature. YA-12ST1 well was planned with sidetracking design utilizing whipstock and hence, tortuous wellpath which leads to high dogleg at the sidetrack point need to be considered. Losses of circulation were observed from historical development campaign of the field. Thus it was essential that extra precautions have been prepared for efficient hole cleaning and consistent penetration control. Other challenges attached with the recommended practices to overcome them including wellbore instability, differential sticking, drag and friction factors were analyzed further in this paper. In conclusion, this paper serves as a reference for future ERD well planning and execution as the overall drilling campaign achieved excellent well delivery performance in term of cost and time. This campaign has been successfully completed with remarkable achievements such as the first semi-submersible tender-assisted drilling rig used by PETRONAS group, huge total cost saving, zero lost-time injury, and successfully secured the reservoir target and meet the gas volume target. The novelty of the successful Yetagun Phase VI development wells project yielded good practices, technology used and excellent project planning that can be applied in future projects. This paper also can be a reference for future ERD well drilling in Myanmar.

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This paper presented the extended reach well construction results to date of 3 infill wells: YA-01, YA- 05ST1, and YA-12ST1 during the Phase VI development drilling campaign in Yetagun gas field, offshore Myanmar which had delivered top-quartile drilling performance throughout every phase of well delivery. The significant changes in drilling practices had led to the overall time and cost savings. Systematic approach to benchmarking drilling performance had been incorporated into the efficiency of the operation based on the Key Performance Indicators. Every phase of drilling, evaluating, and completing high angle wells was analyzed. The main technical hurdles contributed to the success of these wells were drilling practices, mud selection and directional control technique. Section-by-section was being described in the paper taking into account the factors that contributed to a top-quartile drilling performance including wellpath design, hydraulic, bottom-hole assembly design, drillstring design and torque and drag reduction methods. A few offset wells were selected and analyzed in order to act as a benchmark of expected performance, but up-front effort was established by proposing the significant key performance indicators (KPIs) which required specialized resources. Value was generated through performance improvement. Engineering team of the drilling campaign dramatically achieved all the KPIs in the top quartile with zero LTI and successfully secured the reservoir target with the maximum drainage contacts as well as meet the gas volume target. Every aspects of the well design and construction was discussed, challenged and where possible, optimized for further study. The dramatic outcome of the drilling performance always came from the combination of some small incremental improvements and step-change innovations. Statistically analyzing of the KPIs covering the central tendencies and convergence link to the consideration of benchmarks. YA- 05ST1 successfully achieved Best in Class for WCPF and DCPF whereas the DDPTF of all the 3 wells were categorized in Quartile 1 performance. Among the significant changes in drilling practices that contributed to the time saving were the waiving of pilot hole, utilization of casing drive system, installation of tubing isolation Valve-Flapper for completion and implementation of drill to limit approach. Moreover, both the techniques and lesson learnt throughout the campaign were continuously revised, improved and distributed with the aim that the information can be built upon and lead to further improvements in the next extended reach well delivery. In conclusion, the key differences in drilling practices throughout the campaign were proven to be practicable and in fact play an important role in time saving. Since the ERD has become an ever-more important enabling technique to exploit hydrocarbons nowadays, the replication of the best practices and lesson learnt should be shared for future extensive ERD wells planning and executions.